Food Dyes and ADHD

An enduring controversy in the ADHD world is the role of diet and in particular, synthetic food dyes. The idea that food and features of the modern diet are somehow related to behavior problems in children dates at least to the early 20th century. However, the specific proposal of synthetic food dyes (and other features of food) relating to ADHD gained prominence through the work of Benjamin Feingold in the 1970s. Professional opinion on this issue has tended toward skepticism due to limited confirmation in numerous small studies. In 2011 the FDA reviewed the evidence and although they admitted that some children are sensitive to food dyes and this may exacerbate ADHD symptoms, they opted not to take any restrictive action. In contrast, beginning in 2010 European Union countries have added a warning label to foods containing synthetic dyes indicating they may increase inattention or hyperactivity. Currently, the State of California is conducting its own review (full disclosure: I have been asked to consult).

We conducted a thorough review of this literature in 2012 and little has changed since then. We examined the literature in numerous ways—parsing out studies in relation to whether or not they were restricted to FDA approved dyes (many done in Europe or Australia were not), quality of the studies, availability of objective measures, and whether or not the sample of children was preselected to be hyperactive (versus a general population sample of kids) or to have food allergies.

Overview

Overall, we confirmed an effect of food dyes on ADHD symptoms.  This was demonstrated by pooling the effects of randomized trials (that prove causality) and looking at outcomes as reported by parents, by teachers or observers, and on objective tests of attention. The effect was similar in size across these three sources, and reliably non-zero.  The effect was statistically indistinguishable whether in general population samples or in children with ADHD, suggesting a public health problem as much as an ADHD problem. However, the effect was qualitatively larger in children with ADHD or selected to be hyperactive. While the overall effect seems clear enough, there were numerous caveats.

Caveat #1.

Effects are small, not big enough to account for most ADHD nor to view diet control as a substitute for standard care. However, some children may benefit from avoidance of synthetic food dyes.  

Caveat #2.

Studies are small and varied. However, the highest quality studies had the biggest effects.

Caveat #3.

The parent report signal could be due to publication bias (it would take very few unpublished negative studies to reduce the effect to indistinguishable form zero).

Caveat #4.

The important effect on objective tests of attention relies on a very small number of total children studies (less than 150 overall).

Caveat #5. 

There are few studies in the United States not restricted to FDA colors—so we can’t be sure the effect is robust when restricting to FDA approved colors (even though we have little reason to think it would be different).

A major issue:

We identified 10 studies done in the United States. The last one was published in 1981—over 35 years ago. Studies were subsequently done in Australia and Great Britain the 1990’s up until 2007. Yet diets and food content has continued to evolve. In fact, the total amount of synthetic additives in children’s diets is much greater now than it was 35 years ago. Stevens et al, in a 2014 essay, noted, “The amount of AFCs the Food and Drug Administration has certified over the years has increased more than 5-fold since 1950 (12 mg/capita/day) to 2012 (68 mg/capita/day). In the past 38 years, there have been studies of adverse behavioral reactions such as hyperactivity in children to double-blind challenges with AFCs. Studies that used 50 mg or more of AFCs as the challenge showed a greater negative effect on more children than those which used less.”

There is a real probability that these effects are larger than what the older, aggregated literature shows in everyday life. Thus, there is an urgent need for an updated, properly conducted study in the United States. The policy changes in the EU were based heavily on a population study in England; a recent attempt to replicate that study in Hong Kong failed to confirm the effect there. What about the USA?

What Do I Recommend?

The value judgement required by policymakers and parents is this: Do we feed our children products with uncertain safety data until they are definitely proven harmful? Or do we restrict products with uncertain safety data until they are proven safe? The FDA has decided to allow dyes until harm is more definitely proven. The EU has decided to restrict their use until they are proven safe. My own view is that food dyes are not proven safe for children, and certainly may increase symptoms of inattention or hyperactivity. For some children, this may be one too many challenges to their nervous system and contribute to ADHD symptoms.

My own children will not be given food with synthetic dyes if I can help it. While acknowledging that the data are weak, my bias is toward child safety and avoiding needless risks that have little upside. Thus, given they have little value, I recommend parents avoid these food dyes if they can. The synthetic dyes have no nutritional value and are mainly to make processed food more palatable. As I outlined in my book, Getting Ahead of ADHD (Chapter 3), a healthy diet with less processed food is a good idea in general for children, and worth the effort and expense if you can manage it. This is one part of that theme.

The Science

Lancet. 2007 Nov 3;370(9598):1560-7. Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial.McCann D1, Barrett A, Cooper A, Crumpler D, Dalen L, Grimshaw K, Kitchin E, Lok K, Porteous L, Prince E, Sonuga-Barke E, Warner JO, Stevenson J.

J Am Acad Child Adolesc Psychiatry. 2012 Jan;51(1):86-97.e8. doi: 10.1016/j.jaac.2011.10.015. Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms, restriction diet, and synthetic food color additives. Nigg JT, Lewis K, Edinger T, Falk M.

Am J Psychiatry. 2013 Mar;170(3):275-89. doi: 10.1176/appi.ajp.2012.12070991. Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. Sonuga-Barke EJ, Brandeis D, Cortese S, Daley D, Ferrin M, Holtmann M, Stevenson J, Danckaerts M, van der Oord S, Döpfner M, Dittmann RW, Simonoff E, Zuddas A, Banaschewski T, Buitelaar J, Coghill D, Hollis C, Konofal E, Lecendreux M, Wong IC, Sergeant J; European ADHD Guidelines Group.

Nutr Rev. 2013 May;71(5):268-81. doi: 10.1111/nure.12023. Epub 2013 Mar 13. Mechanisms of behavioral, atopic, and other reactions to artificial food colors in children. Stevens LJ, Kuczek T, Burgess JR, Stochelski MA, Arnold LE, Galland L.

Arnold LE, Lofthouse N, Hurt E. Neurotherapeutics. 2012 Jul;9(3):599-609. Neurotherapeutics. 2012 Jul;9(3):599-609. doi: 10.1007/s13311-012-0133-x. Artificial food colors and attention-deficit/hyperactivity symptoms: conclusions to dye for.

Amounts of artificial food colors in commonly consumed beverages and potential behavioral implications for consumption in children. Stevens LJ, Burgess JR, Stochelski MA, Kuczek T. Clin Pediatr (Phila). 2014 Feb;53(2):133-40.

J Dev Behav Pediatr. 2013 Nov-Dec;34(9):642-50. doi: 10.1097/DBP.0000000000000005.Food additives and behavior in 8- to 9-year-old children in Hong Kong: a randomized, double-blind, placebo-controlled trial.Lok KY, Chan RS, Lee VW, Leung PW, Leung C, Leung J, Woo J.

 

Dr. Nigg cannot advise on individual cases for ethical, legal, and logistical reasons.